Petrochemical Steel Pipe Rack: Critical Assessment of Existing Design Code Provisions and a Case Study

The investigation of the seismic integrity of petrochemical plant steel structures should be commensurable to their importance given the high necessity for human life safety and financial robustness. To date, it is demonstrated in the existing literature that still many grey areas of knowledge exist upon the appropriate application of code provisions on non-building structures design. Indeed, the selection of seismic design parameters such as system performance factors or important classes are still vague aspects, in contrast with those for common building structures, either because of the paucity of information of seismic codes or due to the structural peculiarities that characterise the industrial structures resulting in the difficulty of defining ‘all-encompassing’ design parameters. The present paper aims at highlighting those parameters considering also a case-study that pertains to a steel pipe rack. The pipe rack is designed and analysed in the linear and nonlinear regime, both statically and dynamically, according to the Italian and European codes. American code provisions are examined as well so as possible inconsistencies might be found. It is demonstrated that the common nonlinear static analysis (pushover analysis) cannot be used to assess the response of the rack and the behaviour factor selection from current standards could be unjustifiable. Also, common engineering demand parameters, e.g. interstorey drift ratio, need further assessment vis-à-vis the response of nonstructural components of which the current design method does not comply with modern methods.